Problem: The Mothership Core is currently being used offensively. This is not what was intended for the unit.
The current version of the Mothership Core can be very useful for attacking early. The main challenge of doing so is getting it across the board into an attacking position safely, but this is sometimes a moot point because there tends to be so much space along the sides of the map.
Its range 10 allows it to avoid difficulty with every early Terran Anti-Air when positioned over open space. They can snipe Turrets before the turret can fight back, and 1-shot 0 armor marines from range 10. This means that when positioned over opened space near an expansion, the MC can effectively stop mining until Vikings. Once Vikings are available, they do quite well in taking it down, though it takes several Vikings to take down a MC without losing anything (and once you’ve lose something, the MC has traded effectively).
Against Zerg, as Day9 has pointed out in one of his dailies, the early game use of the MC along with a 4-gate seems very difficult to stop – at a time when the only response zerg has to the MC is Queens (which it outranges and generally trades quite well against). Spore crawlers get the same treatment as turrets – they get killed out of range to be effective as anti-air.
In PvP, the ability to use a MC effectively does a couple things. First, it makes the ramp much less of an advantage (since you can’t deny vision with a flying unit around). This can be a big issue playing against blink builds (whose only issue in engaging is vision) which were previously spending 225/175 on one observer to provide a much more fragile form of vision (40 health vs. the 250 of the MC). This provides blink/obs builds the ability to ignore the obs and get 175/125 more to spend on units (detection aside, this makes blink pushes without detection much harder to stop, and executing blink rushes against DTs semi-autoloss… because PvP needed to be more about build order wins, right?). And then, of course, I’m sure there will be a 4-gate recall build on that winter map with the incredibly close air distances (maybe that map won’t make it, or something – pure speculation).
As you can see offensive MC usage, if you can get away with it poses problems in all matchups. Maybe given sufficiently astute play by your opponent you can’t, but that remains to be seen.
How did this happen? Pre-beta, the MC was a unit attached to a building. It didn’t move and therefore you couldn’t attack with it unless you proxied a Nexus (which is a bit much). So why is it being used so much and so offensively now? It’s mobility has changed, so that it can participate in fights in which it didn’t used to be able to participate.
Problem: The Mothership Core has issues with defending. Because its attack is available for only a short window of time – and the cost of using it is a recall or an energize (both of which are ridiculously better in terms of having more units with which to defend later).
One energize on a Nexus is generally 90 seconds of build time over the next three minutes. That’s a little more than 5 probes, (or about 150-200 resources per minute – not to mention about 225-300 resources if you’re able to harvest at the 30-40 rate as probes emerge). If you get your MC around 4 minutes, your first 100 energy will come at about 5:30. You don’t get 100 energy again until 8:30. By 10 minutes, if you used your first Energize on probes, you’re both mining optimally (somehow, haven’t tweak build order stuff yet, but just in theory) and you’re both still making probes, you’re a solid 450-600 resources ahead. That’s a lot of money – It’s a full Colossus or almost two Immortals.
Ok, we’ve established that Energize is good. Recall is good, too (at least worth the cost of the units you save with it, isn’t it?).
Hey, wait a minute, wasn’t I talking about Purify? Here’s the point I’m coming to about Purify. If you need Energy for Purify, you’re not getting one of these other effects – and for what? If you’re not way behind in army size, your opponent will turn tail and run once Purify hits the field – and during that time you get a few marines, maybe a couple marauders, a stalker or two (perhaps none if they have blink), perhaps more than one roach. See how bad that is at defense? Because you can’t force your enemy to stay (with a lot of FFs – and no Medivacs or burrow - or bad positioning on your opponent’s part) once he’s begun attacking. You get nice bursts of dps – but you can’t keep them around for it, so it just goes unused. And if it is high enough that you can cream an army hard enough to make using the ability worth it, what happens when you get it to the front lines and it can be used offensively? (Hint: scroll up a little bit.)
The point is that energy for an attacking mode is great for offense – but not that good for defense, especially if its duration is low.
My solution
There is undoubtedly more than one, but here’s what I’ve decided I like best. The reason it’s become so good offensively is because it’s mobile. The reason it’s so poor at defense is because its attack is so temporary. So what happens if we make the attack passive, and make the movement the part that’s tied to energy use. This has several effects.
1. We can provide the MC with bursts of mobility during defense. Short bursts of attack may be horrible for defending, but short bursts of mobility are great for it. Why else does everyone and their mother get blink near the beginning of a game if they suspect mutas or drop play?
2. The MC is always available for defending. Maybe it’s not a 45 damage/10 range super-cannon, but who’s going to be able to use it as that anyway – if everytime you turn it on an enemy can just decide to engage again 20 seconds later without the super-cannon available?
3. We can limit how much the MC is able to use its mobility by limiting the availability of its movement speed (through energy cost), and thereby eliminate the possibility of getting it across the map for a rush. If it takes the MC five minutes to get across the field on a map like Steppes of War – who cares if its good during the attack? On this note, you can make it worse during the attack, since its passive attack can have effectiveness of something like a photon cannon, rather than requiring a more potent attack due to its limited availability. Oh, and also, for all you zergies, they could also make it take long enough to get across the field for you to be able to have more anti-air available than hydras, or give it a short enough range to be susceptible to spores. This makes it much more defendable in a “rush” (if such thing is still allowed to occur).
4. This may have a slight “Energy tax” at the beginning of the game, in order to get it into defensive position once it emerges from the Nexus.
Example of Concept
Mothership Core
Cost: 50 minerals, 50 gas, 0 supply, 30 build time
Defense: 150 health, 100 shields, 1 armor
Sight: 14
Ground/Air Attack: 20
Cooldown: 1
Range: 7
Speed: 0
Abilities: Recall (as before), Energize (Range extended to 20 due to restricted mobility) and...
Psionic Thrust
Cost: 50 Energy
Description: Psionic Energy propels the motor-less core forward, granting it a movement speed of 1.0 for 10 seconds.